s later. this is getting pretty nasty and -- questions later. this is getting pretty nasty in the case of a real tragedy overseas. >>> thousands of protesters gathered outside the u.s. embassy in cairo to demonstrate against the same film. they scaled the exterior walls and pulled down an american flag. they also tried to raise a black flag with the words there's no god, but allah and muhammad is his messenger. >>> some of the country's most experienced diplomats are graduates of the johns hopkins graduate school of advanced international studies here in d.c. the flag is it at half staff tonight on the washington campus. students say they have learned from experienced professors that foreign service can be dangerous work. daniel serwer, a professor of conflict resolution, adds this. >> we're often grateful to our military. we often forget the civilians who serve abroad and marines' primary responsibility is to protect the information in the embassy. the prime responsibility for the physical protection of the embassy under international law belon